The Storrs strain of muscular dystrophic chickens has been shown to have two immuno-deficiencies, reduced IgG levels and a T cell suppressor (Ts) defect. The Ts defect is inherited as an autosomal recessive and segregates independently from the muscular dystrophy trait. The reduced IgG levels do not appear to aave a genetic basis. From the genetic studies of muscular dystrophy in the chiken model, we hypothesize that the Ts defect influences the time of onset and severity of the muscular dystrophy trait. Studies to test this hypothesis will include: (l) The development of techniques and criteria for establishing a pathological index that will quantitate the degree of muscle destruction in muscular dystrophic chickens, (2) Further in vivo and in vitro examinations of the immune response system in Storrs as well as Davis, California muscular dystrophic ckicken strains, (3) Establishment of a develpmental immune and muscle profile for the Storrs muscular dystrophic chicken strain, (4) Analyses of F2 and testcross progeny for the affects of segregating traits on the pathogenesis of the muscular dystrophy trait, (5) Breeding of muscular dystrophic chickens with a normal Ts for aid in clarifying the relationship of the immunodeficiency and muscular dystrophy, and (6) Immune manipulation of Storrs muscular dystrophic shickens in efforts to alter the onset and degree of muscle destruction.